pipe.js

var insert = require("insert-stream")
    , through = require("through-stream")

var insertInto = insert(rootElem, null)

// Some data source
source.pipe(infiniteScroll()).pipe(insertInto)

function infiniteScroll() {
    return through(write)

    function write(chunk, buffer) {
        var stream = this
        buffer.push(chunk)
        // isBelowScreen logic. not implemented
        if (chunk.isBelowScreen()) {
            // some screen object. not implemented
            screen.on("scrolled", function () { stream.emit("drain") }
            return false
        }
    }
}

wrap.js

var insert = require("insert-stream")
    , proxy = require("proxy-stream")

var insertInto = insert(rootElem, null)

source.pipe(infiniteScroll(insertInto))

function infiniteScroll(stream) {
    return proxy(stream, write, stream.read, stream.end, [writePipe])

    function write(chunk) {
        var res = stream.write(chunk)
        // isBelowScreen logic. not implemented
        if (chunk.isBelowScreen()) {
            // some screen object. not implemented
            screen.on("scrolled", function () { scroll.emit("drain") }
            return false
        }
        return res
    }

    function writePipe(chunk, buffer) {
        var stream = this
        buffer.push(chunk)
        if (chunk.isBelowScreen()) {
            screen.on("scrolled", function () { stream.emit("drain") }
            return false
        }
    }
}